The absorption of electromagnetic energy is one of the most fundamental processes that is used in many different applications, which include photovoltaics, wireless energy transfer, molecular sensing and photodetection. Increasing absorption efficiency is the key to the development of these areas. The phenomenon of total absorption consists of the absorption by the scatterer of all incident energy. Traditional approaches for constructing systems that support total absorption involve the use of extended absorbers or incident fields containing components that rapidly attenuate with distance to the absorber. In this work, we present an approach that allows the coherent total absorption phenomena in individual nanoparticles above the substrate. We demonstrate that it is possible to achieve perfect absorption using a focused beam with some given spatial distribution. This beam corresponds to a set of nanoparticle parameters for which the condition of total absorption is fulfilled. The obtained results are confirmed by full-wave simulations.
Strongly coupled material excitations to optical modes has shown potential to modify the material’s chemistry. The optical modes are usually given by an external cavity, such as Fabry-Pérot cavities, which may limit the scope of applications. Here we highlight the possibility of self-coupling electronic or vibrational resonances to optical modes sustained by the materials themselves. We show electronic and vibrational cavity-free polaritons in concrete examples, such as a slab of excitonic material and a spherical water droplet in vacuum. The abundance of cavity-free polaritons in simple structures points at their practical importance for polaritonic chemistry, exciton transport, and modified material properties.
A new kind of electromagnetic wave, combining the properties of propagating and evanescent waves, is discovered theoretically in a paper by E. Narimanov, published in this issue of Advanced Photonics. The commentary provides context for Narimov’s paper.
We demonstrate that a hybrid c-Si/Au nanocavity can serve as a multifunctional sensing platform for nanoscale (about 100 nm) thermometry with high accuracy (>0.4 K) and fast response (<0.1 second), controlled local optical heating up to 1200 K and also provide Raman scattering enhancement (>10^4 fold). The system has been tested in the experiment on thermally induced unfolding of BSA molecules, plased inside the hybrid nanocavity. Moreover, numerical modeling reveal, that two possible operation modes of the system: with and without considerable optical heating at the nanometer scale, while other functionalities (nanothermometry, RS enhancement, and tracing the events) are preserved. These regimes make the hybrid nanocavity more versatile sensing system than fully plasmonic counterparts. The simplicity and multifunctionality of the hybrid nanocavity make it a promising platform for photochemistry and photophysics applications.
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